Gas pressure alarm system for toll cables



April 26, 1932.

I S. P. SHACKLETON GAS PRESSURE ALARM SYSTEM FOR TOLL CABLES Filed Jan. 27. 1930 INVENTOR 61F. Sims/Ham ATTORNEY of conductors is short-circuited.

Patented Apr. 26, 1932 UNITED STATES PATENT OFFICE SAMUEL Pi SHACKLETON, OF WYOMING, NEW JERSEY, ASSIGNOR T0 AMERICAN TELE- PHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK -'GAS PRESSURE ALARM SYSTEM FOR TOLL GABLES Application filed January 27, 1930. Serial No. 428,884.

This invention relates to indicating means, and more particularly to arrangements of apparatus and circuits for indicating at which one of a number of fixed points a long pair In connection with the testing of long cables, it is the practice to maintain the cable under gas pressure. If this pressure falls below the normal or a predetermined value, it is desirable that an indication be given; accordingly, it is good practice to install at intervals along the cable low pressure alarm contactors or equivalent devices, which operate to shortcircuit a pair of a spare quad and produce a visual or audible signal at the repeater station, for instance, whenthe pressure falls.

The present invention is designed primarily to give a suitable indication of the location of the point on the cable at which the alarm pair is short-circuited. It will be obvious, however, that .the applicants arrangement is broadly applicable to the indicating of the location of a short-circuit at any one of a number of fixed points on an extended pair of conductors. In general, the applicants arrangement comprises a plurality of signaling devices corresponding in number and arrangement to the short-circuiting devices along the cable and means for causing the operation, in response to the operation of one. of the shortcircuiting devices, of the corresponding one of the signaling devices.

The invention will be clearly. understood 'whenthe following detailed descriptionof one desirable embodiment is read with reference to the accompanying drawing, which shows that embodiment in diagrammatic form.

The cable pair shown may be the alarm pair of a square quad, and a, b, c, d and 6 indicate points at which this pair may be short-cir cuited by devices such as low pressurealarm.

contactors. By way of illustration, two alarm contactors .C and C are diagrammatically contact and place a short-circuit on the pair of conductors.

Difierential relays R R R .R, and R correspond to the points a, b, c, d and e, respectively, on the cable pair. Corresponding to these relays are lamps L L L L and L In addition, an auxiliary relay R is provided; this relay should be slow operating. Each of the relays R R R R and R, has its righthand winding in series with, the cable pair, the windingof relay R andla battery 13,. Differentially arranged with respect. to the right-hand winding of each of the relays R to R is a left-hand winding, which may be termed the local winding. The armatures of relays R to R in the released position of the relays, prepare the closing of circuits through the respective lamps L to L and a battery B The connection of the local windings of the relays R to R to the resistance shown at the left of the drawing is to be noted.

If, now, contactor C at point (Z, for in stance, operates to place a short-circuit on the pair at that point, as indicated by the dotted line, the right-hand or line windings of relays R to R, carry current and the relay R is energized. The right-hand armature of relay R prepares a circuit from battery B to the lamps L to L and the left-hand armature of this relay causes the energization of the local windings of relays R to R The resistance is so arranged that, upon the completion of these circuits, the differential relay corresponding'to the point at which, the short-circuit is placed on the cable pair will have equal currents in its line and local windings, whereas the other difierential relays will have difl'erent currents in the two windings. Accordingly, it Will be understood, the appropriate relay will release and its armature will complete the circuit through the corresponding one of the lamps L to L while the remaining lamp circuits will be held open by the operated condition of the respective relays.

In circuit with the battery B and the lamps L to L is thewinding of a relay R, designed to operate with any one of the lamps to close an auxiliary signal circuit.

While the invention is disclosed in one s ecific embodiment, which is deemed desirahle, it is to be understood that it is ca able of embodiment in other and difierent orms 5 within the scope of the appended claims.

What is ciaimed is:

1. In association with an extended pair of conductors and a plurality of short-circuiting devices designed to operate thereon, said 7 short-circuiting devices being located along.

said pair at intervals of considerable length, a plurality oi differential relays c'orresponding in number to said short-circuiting devices, a slow-oprating'reiay, and a lurality oi signaling devices each controlle by one of said difierential relays throu h a. release contact thereof, each of said di erential relays having a first winding in series with the conductors of said pair and the windin of said slow-operating relay and a second winding adaptedto be connected in circuit with a source of volta e and resistances upon the operation of sai slow-operating relay, the arrangement of resistances being such that upon the operation of any one of said short-circuiting devices a certain one of said diiferentialrelays will be released to 0 erate the corres ending signaling device, w e the other di erential relays will operate to prevent the operation of the corresponding signaling devices.

2. In association with an extended pair of conductors and a plurality of short-circuitmg devices designed to o erate thereon, said short-circuiting devices oing located along said pair at intervals of considerable length, apparatus ouped at a single station on the line of sai pair, said apparatus comprisin a plurality of difierential relays correspon ing in number to said short-circuiting devices, a. slowroperating relay, a lurality of si aling devices each controlled by one of sai dif- -ferential relays through a release contact thereof, a source of voltage, and a resistance, each of said difierentiai relays having a first winding in series with the conductors of said pair andthe winding of said slow-operating relay and asecond winding associated wit 0 a particular portion of said resistance and 5 adapted to be oonnected'in circuit therewith and with said source of voltage upon the operation of said slow-operating relay, the particular portion of said resistance associated with each of said second windings being so chosen with reference to the spacing of the short-circuiting devices that upon the operation of any one of said devices a certain one of said difierential relays will have equal currents in its two windings while the other difierential relays will each have unequal currents in its two wind' In testimony whereo I have signed my name to this specification this 25th day of January, 1930. H SAMUEL P; SHKGK'LETON. 

